Definition of Semiconductors
Semiconductors are materials whose electrical conductivity lies between that of conductors, like metals, and insulators, like glass. In electronics, they are crucial because their conductivity can be precisely controlled, allowing them to function as switches or amplifiers in circuits. This property arises from their atomic structure, which features a small energy band gap that electrons can cross under certain conditions, such as temperature or applied voltage.
Key Properties and Principles
The core principles of semiconductors involve their band structure, where the valence band and conduction band are separated by a narrow forbidden gap. Doping, the process of adding impurities, creates n-type (electron-rich) or p-type (hole-rich) semiconductors, enabling the formation of p-n junctions essential for devices. Conductivity increases with temperature or light, unlike metals where it decreases, making semiconductors ideal for temperature-sensitive applications.
Practical Examples
A common example is the diode, formed by a p-n junction in silicon, which allows current to flow in one direction only, used in rectifiers to convert AC to DC power. Another is the transistor, a semiconductor device that amplifies or switches electronic signals, as seen in microprocessors where billions of transistors on a single chip process data in computers and smartphones.
Importance and Applications
Semiconductors underpin modern electronics, powering everything from solar cells that convert sunlight to electricity to LEDs in displays and sensors in medical devices. Their ability to miniaturize and integrate circuits has driven the digital revolution, enabling faster computing and energy-efficient technologies, with ongoing advancements in materials like gallium arsenide expanding their use in high-speed and optoelectronic applications.